Leaf is one of the important organs of plants that facilitates the exchange of water and air with the surrounding environment. The morphological variation of leaves directly affect the physiological and biochemical processes of plants, which also reflects the adaptive strategies of plants to obtain resources. By focusing on several leaf morphological traits, including leaf size, leaf shape, leaf margin (with or without teeth) and leaf type (i.e. single vs. compound leaf), here, we reviewed the relevant research progresses in this field. We summarized the ecological functions of leaf morphological traits, identified their geographical distribution patterns, and explored the underlying environmental drivers, potential ecological interactions, and their effects on ecosystem functioning. We found that the current studies exploring the distribution and determinants of leaf size and leaf margin states mainly focused on single or specific taxon in local regions. Studies have also explored the genetic mechanisms of leaf morphology development. Leaf traits trade off with other functional traits, and their spatial variation is driven by both temperature and water availability. Leaf morphological traits, especially leaf size, influence water and nutrient cycling, reflect the response of communities to climate change, and can be scaled up to predict ecosystem primary productivity. Further studies should pay attention to combine new approaches to obtain unbiased data with high coverage, to explore the long-term adaptive evolution of leaf morphology, and to generalize the scaling in leaf morphology and its effect on ecosystem functioning. Leaf provides an important perspective to understand how plants respond and adapt to environmental changes. Studying leaf morphological traits provides insight into species fitness, community dynamics and ecosystem functioning, and also improves our understanding of the research progresses made in related fields, including plant community ecology and functional biogeography.

Plant traits link environmental factors, individuals and ecosystem structure and functions as plants respond and adapt to the environment. This review introduces worldwide classification schemes of plant functional traits and summarizes research on the relationships between plant functional traits and environmental factors such as climate (e.g., temperature, precipitation and light), geographical variation (e.g., topography, ecological gradients and altitude), nutrients and disturbance (including fire, grazing, invasion and land use), as well as between plant functional traits and ecosystem functions. We synthesize impacts of global change (e.g., climate change) on plant functional traits of individuals and plant communities. Research on plant functional traits is very fruitful, being applicable to research on global change, paleovegetation and paleoclimate reconstruction, environmental monitoring and assessment and vegetation conservation and restoration. However, further studies at large scale and including multi-environmental factors are needed and methods of measuring traits need to be improved. In the future, study of plant functional traits in China should be accelerated in a clear and systematic way.

Trade-offs among different plant functional traits reflect the different strategies of plants in resource acquisition and allocation and have been a hot topic in ecological research in recent years. Starting from research scales, leaf traits, organs, and plant groups, this review briefly introduces how the study of trait relationships has gradually expanded and deepened based on the leaf economic spectrum (LES) in recent decades. 1) Relevant studies have been focused on the species living in extremely harsh environments. LES is relatively stable along environmental gradients studied. Both intra- and inter-specific leaf trait relationships are similar. 2) Leaf decomposition rate and flammability are significantly related to the morphological traits and nutrient contents. The relationship between leaf economic traits and hydraulic traits depends on environmental water availability. 3) Leaf mass per area is coupled with wood density and seed size. However, the morphological traits of leaf are not related to relevant traits of root and flower, indicating that these organs may have evolved independently. 4) LES can well explain the growth/survival strategies of some special vascular plants: invasive plants have relatively high resource use efficiencies and fast relative growth rates, locating on the “low investment-quick returns” end in LES. In contrast, the leaves of the carnivorous plants are capable of catching prey, but have relatively low photosynthetic and growth rates, distributing on the other end of LES. Besides, LES pertains to not only the oldest seed plant cycads but also ferns and poikilohydric plants (bryophytes and lichens). This review summarizes the research progress of this topic and presents some suggestions, hoping to provide some new insights for future studies.

Aims Mangrove plants are usually categorized as true mangrove plants and semi-mangrove plants on the basis of their distribution in inter-tidal regions. However, the identification of some fringe mangrove species found mainly on the landward transitional zones is controversial. Specific leaf area (SLA, leaf area per unit dry mass) and mass- and area-based leaf nitrogen concentrations (N_mass and N_area) are important leaf traits for plants, but relevant comparative research on true and semi-mangrove plants is unavailable. Our objective was to determine differences between the two groups and to classify the controversial species according to their leaf traits. Ultimately, this will assist in the management, protection and utilization of mangrove forest.
Methods Three individuals in similar growth sites were chosen for each species from Hainan Island. Fully expanded mature leaves were sampled from the upper canopy of all plants. Succulence (water content per unit leaf area), SLA, N_mass and N_area of mature leaves were studied for 33 species, representing all but three of the mangrove species in China.
Important findings True mangrove plants accumulated more Cl and water per unit leaf area than semi-mangrove plants, except for Pemphis acidula, Hernandia sonora and Clerodendrum inerme. Cl and water content per unit leaf area of true mangrove plants were generally >2.5 mg·cm^-2 and >2.4 g·dm^-2, respectively. Cl concentrations were positively related to succulence for all mangrove species. True mangrove plants had low SLA (<100 cm ²·g^-1) and high N_area; however, semi-mangrove plants had high SLA (mean of 160.4 cm ²·g^-1). Pemphis acidula had much lower SLA than other semi-mangrove species. Our study suggested that there are significant differences between true mangrove plants and semi-mangrove plants in leaf Cl concentration, succulence, SLA, N_mass and N_area. Heritiera littoralis, Excoecaria agallocha, Acrostichum aureum and Acrostichum speciosum are better classified as semi-mangrove plants, while Acanthus ilicifolius and Acanthus ebrecteatus are classified as true mangrove plants, and Xylocarpus granatum needs further research.

Over the past two decades, society has become increasingly aware of problems of forest degradation. The effects of forest degradation transcend individual countries and now impact global processes. Research on the restoration of degraded forests has become a key issue in global ecology. Of particular concern are the effects of human activities on forest productivity and site fertility, especially as the demands for fuel and timber from tropical forests increase. Removal and burning of biomass causes nutrient losses and changes to the soil’s physical and chemical characteristics. The amount of nutrient loss depends on the intensity of the activities, local environmental factors, and the type and successional state of the forest. If nutrient losses cannot be recovered during regrowth, forests often become degraded through time. Thus, it is important that the nutrient dynamics of human-impacted forests are well understood in order to develop plans for restoration of degraded forests and for sustainable forest management. Most of the primary tropical forests in southern China have been degraded by human activities during the past several hundred years. Factors leading to their degradation include: timber harvesting, unsustainable agriculture, overgrazing by domestic animals, and intensive harvesting for fuel. In extreme cases, the land has become completely denuded. Attempts to reverse this process of land degradation have been initiated in this region of southern China. Over the last few decades, large areas have been reforested with a native pine species, Pinus massoniana, to prevent further degradation to the landscape. Cutting of trees is now prohibited, but harvesting of the understory and collection of litter is still allowed to satisfy local fuel needs. Compared with whole-tree harvests, this practice removes less biomass from the forests; however, as the understory and litter are relatively nutrient-rich, this practice may slow or prevent the recovery of soil fertility and productivity of these forest ecosystems. The objective of this study was to determine the effects of harvesting understory plant species and litter on nutrient accumulation dynamics in a Pinus massoniana forest of subtropical China. The results are used to address the following questions: 1) How are nutrients distributed in plants of this pine forest; 2) What quantity of nutrients are removed annually from the ecosystem by the practice; 3) Is this harvesting practice sustainable or not; 4) What alternative management options are available for continued use to meet fuel needs while at the same time improving site fertility, productivity and regeneration processes; and, 5) How do stressed ecosystems respond when the stressors are removed, that is, how would the forest respond if the harvesting practice was stopped. In order to achieve the objectives above, an experiment was established in a MAB reserve of subtropical China in May 1990. The experiment was a paired-plot design with 20 replicates. Each pair consisted of a treatment (continued harvest) and control (no harvest) plot, 10 m×10 m in size and surrounded by a 10 m wide buffer strip. In the treatment plots, local people continued to harvest litter and understory plants according to local practice (about 2－3 times a year) from the beginning of the experiment in May 1990. The harvesting according to local practice occurred during the period of 1990 to 1995 and was stopped after this time. Control plots were protected from any harvesting. Each set of paired plots was similar in soil, slope, aspect, and elevation. In this paper we report only the results of nutrient dynamics and its responses to human impacts over a ten-year period from 1990 to 2000.

Aims Improvement of end-use quality in wheat (Triticum aestivum) depends on thorough understanding of grain quality and effects of environment (E), genotype (G) and their interaction (G×E). Our objectives were to assess the relative effect of G, E and G×E on main quality traits of wheat grains.

Methods Two experiments were carried out in 2000-2002. In the first experiment, six wheat cultivars representing a wide range of gluten strength (strong-, medium-, and weak-gluten wheat) were planted at five sites with different latitudes (Tangyin 36° N, Wuzhi 35° N, Xuchang 34° N, Zhunadian 33° N, Xinyang 32° N) in Henan Province. In the second experiment, nine wheat cultivars released from nine different provinces were planted in eight provincial locations (Hubei 30º37＇N, Sichuan 30º39＇N, Jiangsu 32º23＇N, Shaanxi 34º18＇N, Henan 34º48＇N, Shandong 36º29＇N, Shanxi 37º26＇N, and Hebei 38º02＇N), representing a wider range of environments.

Important findings Significant genotypic differences in all the quality traits were observed in both experiments, indicating that cultivar selection was most important for desirable end-use quality. Significant environmental variations were observed in all the quality traits in experiment 2, but only in content of protein and gluten, sedimentation value and water absorption in experiment 1, which indicated that location was the second important factor determining wheat quality. From the magnitude of F values we concluded that, for quality traits such as grain hardness, sedimentation value, water absorption, stable period, maximum resistance and extension, genotypic effects were greater than environment effects, while environmental influence on protein content was much greater than that of genotypes in both experiments. But for other quality traits such as flour yield, forming time, mixing tolerance and softness, they were inconsistent in the two experiments. In the first experiment, no genotype-by-environment variations were observed. In the second experiment, though significant influences of genotype-by-environment were observed for grain hardness, ash, water absorption, forming time, stable period and maximum resistance, they were smaller than the main effect of either G or E. Significant differences existed in most quality traits between the two years, mainly caused by weather factors such as precipitation, hours of sunshine and average day temperature in May. Close correlation existed between weather factors and quality traits, indicating that excessive precipitation, fewer hours of sunshine and lower day temperature in May would negative affect grain quality for strong-gluten wheat cultivars.

Aims The temperate grasslands in Inner Mongolia, representing a great diversity in vegetation types (desert steppe, typical steppe and meadow steppe) and function groups (grass/herb, legume/non-legume), are ideal places to test the hypothesized functional trait relationships among plant organs. Our main objective in this study was to test whether plant functional traits vary in a coordinated fashion both within and across organs.

Methods Based on the field observation during July and August in both 2006 and 2007, we measured suites of ecophysiological traits of 42 grassland species from 19 sites in Inner Mongolia. The longitude of the study region ranges from 112.82° to 120.12° (E), and the latitude ranges from 41.76° to 49.89° (N). N and P concentrations, N:P ratios of leaves, stems, reproductive structures, fine roots (diameter < 1 mm) and coarse roots (diameter > 1 mm) as well as tissue density of leaf and fine root and specific leaf area/specific root length were determined.

Important findings At both population and interspecific level, N and P concentrations were positively correlated within each organ. Specific leaf area was negatively correlated with leaf N and P concentrations and tissue density at the population level but not at the interspecific level. Specific root length was negatively related to fine root tissue density at population level. Plants with low leaf or fine root tissue density had leaves or fine roots with high N concentrations and large specific leaf area or specific root length. N and P concentrations as well as N: P ratios were also consistently correlated across all organs, but no correlation between specific leaf area and specific root length was observed. At the population level there existed a weak negative correlation between leaf and fine root tissue density while at interspecific level this relationship disappeared. Grasses had lower N and P concentrations than herbs in leaves, reproductive structures and roots, but not in stems. Legumes had higher N concentrations than non-legumes in all organs, but they showed no significant differences in P concentrations.

Aims Isoetes sinensis (Isoeteaceae) is a critically endangered aquatic fern ally in China. Understanding the genetic differentiation of quantitative traits and local adaptation of the remnant populations should provide insight into the adaptation of different populations to their local environment and useful information for formulating appropriate conservation strategy.
Methods The quantitative traits of nine isozyme multilocus genotypes from three remnant populations of I. sinensis were investigated using nested analysis based on random block design in common-garden experiments. Population differentiation of allozyme (F_ST) and quantitative traits (Q_ST) were estimated using the Bayesian approach.
Important findings Of 14 quantitative traits examined, ten were found to be significantly different among populations and three were significantly different within populations. Multiple comparison by Turkey tests indicated that the mean values of five traits were the highest for the Songyang population and lowest for the Xiuning population, whereas the mean values of the macrosporangium characteristics and plant height were highest for the Jiande population and lowest for the Xiuning population. This result probably reflected different scenarios of founder effect, habitat competition ability and trade-off between vegetative and reproductive growth. Local adaptation was evaluated as a difference of Q_ST vs. F_ST value, and eight important reproductive fitness traits were found to be significant (Q_ST>F_ST, p≤0.05 ) under the selfing assumption, suggesting local adaptability in the remnant populations. It is more likely that there is a potential risk of outbreeding depression if genetic enhancement is implemented by translocation of individuals from different populations. Therefore, translocation among these remnant populations is not recommended. Instead, we recommend increasing gene flow within each population and improving habitat management by reducing competition with companion species in in situ conservation for Xiuning and Songyang populations. In the case of Jiande population, minimizing human disturbance should be considered as a top priority and an in situ conservation plot should be designated for the population.

Leaf venation is the distribution and arrangement pattern of a leaf vein system. Earlier studies of leaf venation mainly focused on its taxonomic significance. In recent years, studies of leaf venation functional traits and their significance in plant water relations have been popular topics of plant ecological research. In this paper, we introduced an index system of leaf venation functional traits (including vein density, vein diameter, distance between veins and loopiness of veins). We also reviewed three aspects of leaf venation functional trait studies: relations between leaf venation functional traits and leaf vein system functions (i.e., water-nutrient-photosynthetic product transport, mechanical support and herbivore defense), positive and negative correlations between leaf venation functional traits and other leaf functional traits (e.g., leaf mass per area, leaf lifespan, leaf photosynthetic rate, leaf size and stomatal density), as well as relations between leaf venation functional traits and environmental factors (e.g., precipitation, temperature and light). In addition, leaf venation functional traits can be employed in studies of palaeoclimate reconstructions, watershed and urban transportation planning, as well as global change studies. Since leaf venation functional traits are products of both environmental factors and genetic factors, future leaf venation functional trait studies at molecular-leaf-plant-ecosystem scales are needed, and analyses of plant water relations between leaf venation functional traits and traits of other plant tissues or organs (i.e., stomata, wood and root) also need to be improved. All of these studies show promise in providing new insights into predicting responses of plants and ecosystems to global changes.

Elevated CO₂ concentrations and temperatures under global climate change scenarios projected for coming decades could impact bread wheat (Triticum aestivum) quality. Hence, there is a need to understand the effects of these environmental factors on crop quality. The objective of this study was to experimentally test the effects of elevated CO₂, temperature, and their interactions on wheat grain quality characteristics relevant to its processing, including grain protein content, wet gluten content, sedimentation value, and falling number (alpha-amylase activity). Bread wheat ('Liaochun 10') was field grown in CO₂ and temperature gradient chamber (CTGC) and ambient controlled temperature gradient chamber (TGC). The results indicated that elevated CO₂ concentrations (433.3 to 610.2 μmol·mol^-1) had negative effects on grain protein content, wet gluten content and sedimentation value of bread wheat, but gradual temperature increases (2 ℃ range) had positive effects on these three main quality characteristics. The interaction between gradual increases in CO₂ levels from 433.3 to 551.5 μmol·mol^-1 and temperature increases (+2 ℃ range) showed a similar benefit on grain protein content, wet gluten content and sedimentation value of bread wheat, but when CO₂ concentrations approached 610.2 μmol·mol^-1 and mean daytime temperature increased more than 2 ℃, the interaction of CO₂ and temperature had a negative effect on the three bread wheat quality characteristics. In addition, under CO₂ concentrations of 433.3-610.2 μmol·mol^-1 and gradually increasing temperatures, CO₂ enrichment reduced alpha-amylase activity of bread wheat whereas elevated temperatures and the interaction of elevated CO₂ and temperature enhanced alpha-amylase activity of bread wheat.

Aims Studies on the relationship between leaf and fine root traits provide insights into interactions among plant functional traits, plant strategy for resource acquisition and mass partitioning, and predictive models for fine root traits. Our main objectives were to test if leaf and fine root traits vary in a coordinated pattern in typical temperate grassland and to determine to what extent inter- and intra-specific leaf and fine root traits exhibit structural and functional convergence.

Methods During July and August 2006, we measured nitrogen (N) and phosphorus (P) concentrations, N:P ratios of leaves and fine roots (diameter < 2 mm), specific leaf area and specific root length of 65 grassland species in Xilin River Basin, Inner Mongolia. We statistically analyzed correlations between leaf and fine root traits among and within species.

Important findings At the inter-specific level, N concentrations, P concentrations and N:P ratios of leaves and fine roots were significantly correlated, while specific leaf area and specific root length showed a weak relationship. Species from different functional groups differ in the correlation pattern. In dicotyledons there was a strong correlation between leaf and fine root N concentrations, but not in P concentrations. In contrast, monocotyledons had a positive relationship between leaf and fine root P concentrations, but not N concentrations. Observed inter-specific correlations between above and belowground traits weakened or disappeared when examined at the intra-specific level. Thus, leaf and fine root traits were generally correlated among species, while correlations were weak within species.

Aims Our objective was to determine 1) the phenotypic variation of cone and seed in natural populations and 2) the relationship between phenotypic variation of natural population and different distribution areas in Picea crassifolia.
Methods Field investigation and analysis of the natural distribution of P. crassifolia in Qilian Mountain led to our selection of four cone characters and four seed traits in 10 trees from each of 10 populations. We examined morphological diversity among/within populations based on analysis of eight phenotypic traits. Variance analysis, multi-comparison, correlation analysis and hierarchical cluster analysis were used to analyze experimental results.
Important finding Analysis of variance for all traits showed significant differences among/within populations except for cone dry weight and cone length/cone width. The mean phenotypic differentiation coefficient (Vst) among populations was 27.18%, compared to 72.82% within populations. In different individuals within populations, the CV of cone length, cone width, cone dry weight, cone length/cone width, seed length, seed width, seed length/seed width, 1 000 seeds weight was 10.08%, 5.80%, 19.29%, 9.66%, 8.38%, 15.34%, 6.52% and 13.94%, respectively. Most of the cone and seed traits were positively correlated. The cone dry weight, seed length, 1 000 seeds weight, cone length, cone width were thought to be the most important cone and seed traits that were easy to measured in P. crassifolia. The spatial variation of traits of natural populations was related most strongly to longitude. According to UPGMA cluster analysis, the 10 populations of P. crassifolia could be divided into four groups. This study indicates that there is rich phenotypic variation of cone and seed in natural populations of P. crassifolia in Qilian Mountain and thereby provides theoretical references and basic data for genetic resources conservation, utilization and improvement in P. crassifolia.

Aims Pinus densata is an important forest species in the high mountains of the southeastern Tibetan Plateau. Previous investigations demonstrated that this pine originated through natural hybridization between P. yunnanensis and P. tabulaeformis. The mechanisms underlying this hybrid speciation and especially its adaptive evolution are poorly understood. Reproductive fitness plays a critical role in hybrid speciation; however, the fitness of P. densata in the high plateau environment has not been investigated.

Methods We investigated 13 cone and seed characters, related to reproductive potential of the species, from six representative populations distributed throughout its natural range. The 13 characters are cone length, number of scales per cone, number of fertile scales, cone scale density, fertile scale density, ratio of fertile scales, number of seeds per cone, seed length, length of seed wing, total seed length per cone, total length of seed wing per cone, seed productivity per cone and ovule abortion rate. Patterns of variation of these characters were analyzed using one-way ANOVA and correlated to geo-ecological factors of each population.

Important fingdings Characters, such as cone length, total number of scales in a cone and number of seeds per cone in P. densata were similar to that in P. tabulaeformis, P. yunnanensis and several other species of Pinus. The maximum mean value of seed productivity per cone was 74%. One-way ANOVA showed significant (p<0.01) differentiation in all 13 characters among the six populations. Correlation analysis between cone and seed characters and geo-ecological factors indicated that total number of cone scales, number of fertile scales, number of seeds per cone and ratio of fertile scales were negatively correlated with latitude and seed productivity was positively correlated with longitude and ecological gradient axes. All results suggested thatP. densata as a hybrid species is not inferior in reproductive fitness in the plateau environment. The patterns of geographic variations in cone and seed characters seem to be related to the genetic background and divergent ecological environments of the populations.

Comprehensively understanding the mechanisms underlying the formation of ecosystem services is a prerequisite for maintaining the sustainable supply of ecosystem services. Plant functional traits directly participate in a variety of ecosystem processes, which in turn affect the supply of ecosystem services. Revealing the relationship between plant functional traits and ecosystem services is an important way to understand the formation mechanism of ecosystem services. Based on a systematic literature review, 86 papers on plant functional properties and ecosystem services were retrieved in the Web of Science database, and data for 466 pairs of plant functional traits and ecosystem services and 83 plant functional traits were collected. The current status of research on the relationship between plant functional traits and ecosystem services was revealed. Moreover, the main plant functional traits that affect different ecosystem services and their mechanisms underlying their impacts were also demonstrated. The results show that the research on the relationship between plant functional traits and ecosystem services mostly focuses on natural ecosystems such as grasslands and forests. Most of these studies focus on ecosystem products providing and supporting services, including biomass, net primary productivity, and soil fertility. Based on the impacts of plant functional traits on different ecosystem services, the plant functional traits can be clustered into five categories: soil-conservation-related traits, water-cycle-related traits, ecosystem- multifunction- related traits, product-providing-related traits, and pollination-biocontrol-related traits. The impacts of climate change, human activities, and variations in spatial and temporal scales on the relationship between plant functional traits and ecosystem services need to be further explored.

Aims Our objectives are to determine allometric relationships between petiole mass and lamina mass, area, and volume in different bioclimatic zones and to detect the effect of plant functional types on the relationships.
Methods Typical and zonal mature forests were selected from boreal Huzhong, temperate Changbai Mountain, warm-temperate Dongling Mountain, subtropical Gutian Mountain, Shennongjia and Dujiangyan in China, and one 1 hm² plot was investigated at each site. Traits of lamina and petiole of the dominant woody species were measured in August 2009. The relationship between lamina and lamina support was analyzed by the Standardized Major Axis estimation (model type II regression) with software (S)MATR Version 2.0.
Important findings Statistically significant allometric scaling relationships were found between petiole mass and lamina mass, area, and volume in all functional types and climate zones, with common slopes of 0.82, 0.70 and 0.80, respectively, all of which significantly departed from 1.0. Shrubs had greater lamina volume at a given petiole mass than trees, but the lamina mass and area they support were not significantly different. Evergreen species were observed to have greater lamina mass and lamina volume than deciduous ones, whereas deciduous species had a greater lamina area at a given petiole mass than evergreen ones. With the exception of Shennongjia, the species in subtropical sites were found to have greater lamina mass, lamina area, and lamina volume than temperate sites at a given petiole mass. However, the petiolar support efficiency in the subtropical climate of Shennongjia was close to sites in temperate climate. Our results indicate that the petiole constrains the maximization of lamina size (including mass, area and volume) and that the allometric relationship between lamina and lamina support varies with plant functional type, climate and habitat.

Aims The trait-based community ecology approach has recently attracted considerable interest from plant ecologists. Our objective is to explore variations and correlations of plant functional traits at the species and community levels along a successional gradient in Karst area of central Guizhou Province in order to improve our understanding about community succession from the perspective of functional ecology.
Methods We investigated species composition of 26 plots in three successional stages (bush, deciduous broad-leaved forests, deciduous-evergreen forests) in Karst area of Puding, central Guizhou Province and quantified three functional traits (leaf area, specific leaf area and maximum height) of 82 woody species in these plots. We calculated the species abundance-weighted mean community trait values and used trait-gradient analysis (TGA) to analyze species functional trait variation along the successional gradient and within communities.
Important findings We found an increasing trend in mean community leaf area and maximum height and decreasing mean community specific leaf area along the successional gradient. For mean plot trait values, there were strong positive correlations between leaf area and maximum height, and significant negative correlations between specific leaf area and both maximum height and leaf area. Species β trait values of the three traits were strongly correlated with each other, but there was no significant correlation for α trait values. Results indicate that the adaptive strategies of dominant species transformed from fast growth to high resource-use efficiency along succession and that co-occurring species in the same community employ different trait assemblies.

Aims The aims are to characterize key plant functional traits and their interactions of woody species growing in special and harsh karst habitats, and to explore their potential ways in adapting harsh karst habitats.

Methods A comprehensive survey of nine plant functional traits (including above- and below-ground ones) was conducted in a 100 m × 30 m permanent plot in the Tianlongshan Mountain of Puding County, central Guizhou Province, southwestern China in the summer 2016. Five dominant tree species (Carpinus pubescens, Machilus cavaleriei, Itea yunnanensis, Platycarya strobilacea, Lithocarpus confinis), three shrubs (Zanthoxylum ovalifolium, Stachyurus obovatus, Rhamnus heterophylla) and two vines (Rosa cymosa and Dalbergia hancei) in an evergreen and deciduous broadleaved mixed forest were chosen as target species. Nine traits of leaf, stem, branch and root were investigated and measured. Key features of these nine functional traits of ten woody species were numerically characterized. Traits variations among plant species, life form and leaf phenology group were further investigated. Relationships among key functional traits and between above- and below-ground traits were statistically analyzed.

Important findings (1) Nine traits varied in varying degrees. The maximum and minimum coefficient of interspecific variation were the fine root tissue density (FRTD) and twig dry-matter content (TDMC), 96.47% and 11.67%, respectively. Similarly, the largest and smallest coefficients of intraspecific variation were also FRTD and TDMC, 51.44% and 6.83%, respectively; (2) At the interspecific level, among different species FRTD had no significant difference, but other traits including specific root length (SRL), leaf thickness (LT), leaf area (LA), specific leaf area (SLA), leaf dry-matter content (LDMC), leaf tissue density (LTD), TDMC and twig tissue density (TTD) showed significant differences (p < 0.01). At the intraspecific level, however, SLA showed significant difference, and differences of other traits were not significant. (3) There was a significant correlation between most leaf and branch traits, and SRL vs. SLA were negatively correlated. However, there was no significant correlation among other root traits and leaf and twig traits. In a word, compared to the functional traits in tree species of non-karst evergreen broad-leaved forests in the same latitude, karst woody plants in Puding had a series of functional traits, such as smaller LA, SLA and larger LDMC and LTD and so on, which are beneficial to reducing transpiration and storing nutrient. This may be its main ecological strategy for adapting to arid and poor karst environments.

Aims Liquidambar formosanais a fast-growing and multipurpose native tree species in China. Our aim is to determine the phenotypic variations, adaption and distribution patterns of seed and fruit characteristics of L. formosana populations.

Methods Data for 10 phenotypic traits of seeds and fruits including fruit diameter, peduncle length, thousand kernel weight, seed length, seed width, seed wing length, seed wing width, seed width ratio, seed wing width ratio, ratio of seed length and seed wing length, were sampled from 36 natural L. formosana populations across China. Analysis of variance (ANOVA), correlation analysis, and regression analysis were used to analyze the phenotypic variations among and within populations.

Important findings Results showed that the mean phenotypic differentiation coefficient was 57.55%, which indicated that the phenotypic variation among populations was the main source of the phenotypic variation in L. formosana. The mean coefficient of variation was 15.83%, ranging from 10.05% to 24.31%, suggesting that the phenotypic variation of seeds and fruits was very plentiful. The coefficient of variation was different among populations. The mean coefficient of variation in Anfu was the highest (16.73%), while that of Jianyang was the lowest (11.48%). The pattern of geographic variation of most seed and fruit phenotypic traits was random. There was no significant correlation between the adjacent populations in phenotypic traits. The mean temperature in January, altitude and latitude played important roles in affecting the phenotypic traits. The length-width ratio of seeds decreased with the increase of altitude, which can be used to infer the altitude of the distribution of a population. Our results provide useful information for the collection of wild resources and the breeding of this economically important species.

Aims Shrubs play important roles in both forest and bushland ecosystems. This study aims to identify the adaptative strategies of shrubs in different habitats by analyzing the differences in functional traits of shrubs grown in understory of forest communities and in two bushlands.
Methods Nine functional traits for leaves and twigs were measured on samples collected from the dominant shrub species in 24 plots distributed in three contrasting habitats: forest understory, low mountain bushes, and bushes on the mountaintop, in Beishan Mountain of Jinhua, Zhejiang Province. The overall differences among habitats, inter- and intra-specific variations, and differences between life forms in the functional traits of shrubs were tested by statistical analysis.
Important findings The nine plant traits differed for shrubs grown in the three habitats. The shrubs in forest understory had higher leaf area (LA) and specific leaf area (SLA), lower leaf dry-matter content (LDMC), leaf tissue density (LTD) and twig tissue density (TTD), while those in low mountain bushes had greater leaf thickness (LT) and LTD, smaller SLA and twig dry-matter content (TDMC), compared with shrubs from bushes on the mountaintop. The inter- and intra-specific variation coefficients of SLA, twig diameter (TD), TTD, and TDMC were greatest in shrubs of the forest understory, whereas the inter- and intra-specific variation coefficients of SLA, LDMC, TDMC, and TTD were smallest in ​​shrubs of low mountain bushes. Among different life forms, the understory evergreen shrubs had significantly higher LT, LTD, and LDMC, and lower SLA, than that of deciduous shrubs. The differences in LT and SLA between evergreen and deciduous shrubs of the mountaintop bushes were the same as the understory shrubs, but the differences in LTD and LDMC were reversed. Species and its interaction with habitat are the major factors affecting the shrub traits. In short, compared to the shrubs from bushes, the understory shrubs in forest communities form a series of trait combinations with greater LA and SLA, and smaller LTD, TTD and LDMC for faster growth in order to adapt to the understory environment with less light and stronger competition; this is a quick investment-return (resource acquisitive) strategy. Shrubs from low mountain bushes and the mountaintop bushes are associated with a series trait combinations with greater LT, LTD, LDMC and TTD, and smaller LA, SLA for storing more nutrients and growing slower; this is a slow investment-return (resource conservative) strategy. Different combinations of shrub functional traits and their various life strategies can provide guidance to the ecological restoration of degraded vegetation in the subtropical region of China.

Aims We studied the relationships between functional traits of Quercus species and their responses to meteorological factors in the temperate zone of the North-South Transect of Eastern China (NSTEC), with the objective of finding the dynamics of the relationship between plants and environment.

Methods We measured functional traits of Quercus dominant trees in their eleven core habitats in the temperate zone of NSTEC and analyzed relationships among the traits and their responses to meteorological factors.

Important findings Although leaf mass per area (LMA) and leaf dry matters content (LDMC) could indicate life strategy of the Quercus trees, the implications of LMA was more obvious. The relationships among leaf nutrients based on area were more significant than those based on weight, and the relationships between leaf nitrogen and phosphorus contents were more significant than their relationships to potassium content except for the relationship between phosphorus content per leaf area (P_area) and potassium content per leaf area (K_area). This could be interpreted that potassium does not take part in synthesizing stable structural materials directly in plants. Mean annual temperature (MAT) and mean annual sunlight (MASL) were the main meteorological factors that affected the relationships among functional traits. Compared to leaf nutrients based on weight, those based on area were affected more by MAT and MASL. Mean annual rainfall (MAR) had an effect only on the relationships between P_area and other traits.

Wild soybean is the progenitor of soybean, sharing the gene pool of soybean. In this paper structure and geographical distributions of the natural populations of wild soybean in Hebei Province were analyzed using some important quantitative traits. Coefficients of variation within populations were greatest for 100-seed weight (46 % ) followed by fat content (17 % ), flowering time (10.3 % ) and protein content (4.7% ). Within-population mean flowering times were related to latitudes, but 100-seed weight, fat and protein contents were not. Every population had some individual plants with outstanding differences in character performances that had virtually been caused by the accumulation of gene frequencies for quantitative characters. It was observed that there were different genotypes for genetic flexibility in flowering photoperiodic response, although the populations had always been subjected to the same photoperiodic induction. A similarity analysis of the natural populations indicated a relationship between the quantitative structures of populations and their geographic and ecological distribution areas--showing distinct ecological groups in wild soybean.

Aims Stipa purpurea is the dominant species in alpine arid and semi-arid grasslands on the Tibetan Plateau. Our objectives are to determine if this species exhibits a strategy shift in its specific leaf area (SLA) to nitrogen (N) concentration relationship along a rainfall gradient and to detect possible effects of environmental factors on related leaf traits.
Methods We investigated variations in leaf traits of S. purpurea associated with climatic and soil factors along an east-west transect with a rainfall gradient (69-479 mm) but similar altitudes (4 300-4 700 m). Five locations from east to west are Damxung, Namco, Gêrzê, Mount Qomolangma and Rutog. We measured SLA, mass- and area-based leaf N concentration (N_mass, N_area), leaf density and thickness and soil total N along the transect.
Important findings In pooled data, SLA and N_mass varied little with the growing season mean temperature and precipitation and the soil total N concentration. The SLA-N_mass relationship in S. purpurea did not shift between the semi-humid areas (ratio of rainfall to evaporation > 0.11) and the arid and semi-arid areas (ratio < 0.11), although there was a positive correlation between SLA and N_mass across the five locations. Variation in SLA was mainly determined by leaf density in the semi-humid areas and by leaf thickness in the arid and semi-arid areas; both were negatively correlated with SLA. With increasing temperature or declining precipitation, leaf density decreased and leaf thickness increased, leading to non-significant relationships between SLA and climatic factors. The increase of leaf density in the semi-humid areas was correlated with the increase of N_area, but the increase of leaf thickness in the arid and semi-arid areas did not lead to change of N_area, resulting in unchanged N_area along the rainfall gradient. A positive correlation was detected between aboveground biomass and N_area in S. purpurea, indicating that increased N_area may increase plant productivity. Our findings suggest that alpine plants in arid and semi-arid areas may maintain a constant N_area by increased leaf thickness in order to achieve a similar photosynthetic productivity and water use efficiency compared to the relatively humid areas. The relative impacts of leaf density and leaf thickness on SLA shifted between the semi-humid areas and the arid and semi-arid areas, which may provide insight in detecting the threshold of water limitation in alpine grasslands.

AimsExploring spatial variations in leaf traits and their relationships with environmental properties is crucial for understanding plant adaptation strategies and community assembly. This study aimed to reveal how leaf traits varied spatially and the role of environmental factors.MethodsThe study was conducted in a 5-hm² forest plot in Tiantong, Zhejiang Province. Three leaf traits, including individual leaf area (ILA), specific leaf area (SLA), and leaf dry matter content (LDMC) were measured for 20253 individual trees with diameter at breast height (DBH) ≥1 cm. Soil properties measured included contents of soil total nitrogen, soil total phosphorus, soil total carbon, soil pH value, soil volumetric water content, bulk density, and humus depth. Topographic variables measured included elevation, slope and convexity. We used geostatistical analysis to reveal spatial variations of the three leaf traits. Relationships between leaf variability and environmental factors were analyzed using principal component analysis (PCA) and Pearson’s correlation.Important findings Spatial variability followed the order of ILA > SLA > LDMC. Spatial autocorrelation of three leaf traits was weak within a distance of 5.16 m. The optimal model of the semi-variogram function was Gaussian model for ILA, and exponential model for SLA and LDMC. ILA showed the largest variability at the direction of northeast-southwest, and smallest variability at the direction of northwest-southeast. In contrast, SLA and LDMC had the highest variability at the direction of northwest-southeast and least variability at the direction of northeast-southwest. There were significantly negative relationships between ILA and topographic factors (r = -0.12, p < 0.0001), and between SLA and soil nutrients (r = -0.16, p < 0.0001). In contrast, LDMC was positively correlated with soil nutrients (r = 0.13, p < 0.0001). Relative to soil nutrients, topographic factors affected much more variations in ILA, SLA and LDMC at the direction of northeast-southwest. Distinctly, at the direction of northwest-southeast, variability of ILA was affected mainly by topographic factors, while soil nutrients resulted in the most variability of SLA and LDMC. In conclusion, leaf traits varied considerably with spatial direction in the studied forest plot. Associations between leaf traits and topographic factors and soil nutrients indirectly indicated effects of environmental filtering on community assembly.

Aims The traits of seedlings are often directly related to the performance and function of adult plants in an ecosystem. Measurements of seedling traits are easy and accurate compared to adult traits. Many studies have been conducted on the trait-based assembly of trees in tropical forests in recent years; however, studies on functional traits of seedlings with diameter at breast height (DBH) < 1 cm are scarce. Our objective was to explore the variation of functional traits of woody seedlings in the old-growth tropical lowland rain forest on Hainan Island, China.
Methods We selected the 16 most abundant species of woody plant seedling with a DBH < 1 cm. They represented three growth forms: trees (nine species), shrubs (three species) and lianas (four species). They were also grouped into four growth stages according to the seedling height ( H) classes: I (5 ≤ H < 20 cm), II (20 ≤ H < 40 cm), III (40 ≤ H < 80 cm) and IV (80 ≤ H < 120 cm). The major functional traits of these seedlings, specific leaf area ( SLA), leaf mass fraction (LMF), specific stem density (SSD) and stem mass fraction (SMF) were measured. We assessed the variation in seedling functional traits among different growth forms and height classes and examined the correlations among functional traits.
Important findings There were significant differences among varied growth stages in seedling functional traits.SLA and LMF decreased gradually, butSMF increased with the growth stages of seedlings. SSD was lowest in the first growth stage, but showed no significant difference among the subsequent three growth stages. There were no significant differences between trees and shrubs for any functional traits. Seedlings adapt to the stressful rainforest understory environment (such as low light) by decreasing SLA andLMF and increasing SMF. However, lianas adapt to the environment through the opposite strategy. There were significant correlations between the different functional traits of seedlings. Our study suggests that the seedlings of different growth forms in the tropical lowland rainforest adapt to their environment by changing the value of different functional traits.

Aims Pinus sylvestris var. mongolica (Mongolian pine) is one of the main tree species used for forestation in the northern China and grows well in the early growth stage on sandy lands in the semi-arid area. In recent years, some of trees of Mongolian pine plantations in the sandy lands have been found to be degraded. Study of foliar traits is key to understanding the adaptability and survival strategy of this tree species on sandy land. Our major objective is to examine the impact of needle age on the main eco-physiological foliar traits of Mongolian pine in Horqin sandy land and thus to highlight the importance of needle age for coping with water and nutrients in the semi-arid area.
Methods We chose trees of Mongolian pine planted in early 1980s on a sand dune in the southern margin of Horqin sandy land, located in the permanent experimental plot of the Naiman Desertification Research Station, Cold and Arid Regions Environment and Engineering Research Institute, Chinese Academy of Sciences (42°55′ N,120°43′ E). We measured foliar photosynthetic rate, transpiration rate, carbon content, nitrogen content and morphological parameters (leaf length, width and thickness) for different-age needles. Based on these measurements we calculated transpiration coefficient (K_c) and photosynthetic nitrogen use efficiency (PNUE).
Important findings Net photosynthetic rate (P_n), K_c and PNUE varied among different needle ages and were significantly lower for 4-year old needles than 1-, 2- and 3-year old needles. This can be accounted for by foliar nitrogen content, with decrease in nitrogen leading to the decline in photosynthesis. Strong correlations were found between foliar form (e.g., leaf length, width, thickness and specific leaf area) and precipitation of the year prior to leaf formation and between foliar carbon content and precipitation of the year prior to leaf formation. In terms of transpiration coefficient and PNUE, juvenile needles (mainly 1- and 2-year old needles) were more efficient in using water and nutrients than old needles (4-year old needles), and hence a tradeoff between juvenile and old needles in water and nutrient use is a mechanism for growth and survival of Mongolian pine on sandy land. In addition, shedding old leaves under environmental stresses, as we observed in the field, has significant implication for this species to adapt to harsh habitat in the semi-arid area.

Functional biogeography studies the spatio-temporal variations in patterns of traits and functional diversity, their ecological determinants and effects on ecosystem functioning. With the exponential growth in trait data, this field has developed rapidly in the recent decades and made major progress in exploring the response of species distribution, community structure and composition, and ecosystem properties on environmental changes based on traits. In this paper, we reviewed core objectives, historical developments, main research advance and future directions in the field of plant functional biogeography. Traits are the focus of research in functional biogeography. Here, we first described major findings on the spatial patterns of key traits in plant organs (i.e. leaves, stems, roots, and flowers, along with fruits and seeds) to the whole plants, and their relationships with environment, showing that traits variations are the results of plant adaptive evolution and environmental filtering. Secondly, we summarized the indicators of functional diversity, assessed the spatial distributions of functional diversity, and identified their determinants. We also summarized the main data sources of traits and related gap-filling approaches. Next, we reviewed trait associations and trade-offs among and within organs as well as in the entire plants, focusing on the global leaf economics spectrums and wood economics spectrum, and pointing out the strategies of plants to obtain and allocate important resource (i.e. carbon, nutrients and water). We summarized how trait-based approaches help to predict species distribution, and the link between trait diversity with ecosystem functions. We highlighted the challenges in current research and emphasized the importance to focus on the coordination and trade-offs among multiple traits along with both inter- and intra-specific trait variation in future research, transferring species-based models to individual-based ones, and to adopt approaches like trait networks to quantify the links among traits and their response to environmental changes, further to explore adaptation of plants across scales. Meanwhile, we suggested potential improvement in application of current research advances, which may be useful in constructing next-generation vegetation models and guiding the function-based conservation of plant diversity in future research.

Functional traits influence ecosystem services through their effects on ecosystem attributes, processes and their maintenance. Research on the relationship between functional diversity and ecosystem function can contribute to investigating the mechanism of ecosystem functioning and services supplied, which provides insight on ecosystem services. This study reviewed research on functional traits and framework of ecosystem services, relationship between functional diversity and ecosystem function and application of functional traits in ecosystem services. We proposed a framework of ecosystem services based on functional traits. First, abiotic factors and functional diversity indices that significantly affected ecosystem function should be investigated. Second, (a) quantitative relationships between abiotic factors and functional indices and ecosystem function and (b) quantitative relationships between ecosystem function and ecosystem services should be developed. Third, quantitative relationships between functional diversity and ecosystem services should be constructed. At the same time, community assembly theory and species co-existence mechanism should be incorporated into the investigation of the mechanism relationship between functional diversity and ecosystem function to analyze the mechanism of formation and variation of ecosystem services. The results of ecosystem services based on functional traits can support a scientific basis for the process of decision-making in ecosystem management.

Aims Plant-herbivore interaction is a hot topic in the study of biodiversity and ecosystem functions. Herbivores can negatively affect seedling growth and therefore can alter the dynamics of plant recruitment. However, previous studies do not fully reveal the relative importance of different plant functional traits on herbivory intensity and rarely link herbivory to the relative abundance of plant species.Methods Here, we measured 11 plant functional traits and the relative abundance of seedlings of 16 common woody species in the subtropical forests on 29 islands in Thousand Island Lake, East China. We then used multivariate regression and variance partitioning to test the contribution of functional traits and the relative abundance to interspecific differences of insect herbivory intensity.Important findings Our study found that both plant functional traits (e.g. carbon nitrogen ratio, leaf thickness) and the relative abundance of woody species played important roles in herbivory intensity, and they jointly contributed 54% of the variance of the interspecific differences. Among these factors, species with higher defensive ability, lower nutrient content and higher relative abundance had lower herbivory intensity. We suggest to consider both individual level traits (functional traits) and community level attributes (the relative abundance) in future herbivory studies.

Aims Adaptation of plants to their habitats through phenotypic plasticity in which they trade off various kinds of functional traits is an important ecological strategy. Whereas plant functional traits and its effects on grassland ecosystem functioning have received much attention, the importance of grazing effects on functional traits is poorly understood. This study, therefore, aimed to analyze the responding model of Leymus chinensis functional traits to long-term grazing in semi-arid grassland.
Methods The study was conducted in a field experiment involving treatments with various grazing and enclosure schemes in Nei Mongol. We compared the effects of long-term enclosure, short-term enclosure (SE), moderate grazing (MG), and heavy grazing on plant functional traits in L. chinensis. Partial Least Squares Regression was used to analyze the contributions of controlling factors on changes in biomass in response to grazing.
Important findings The size of L. chinensis became smaller in plots subject to long-term grazing compared with in the plots of enclosures. It had a significant conservative property of plant dwarf which can be found in the SE plot. Interestingly, the variability increased significantly with the increasing of plasticity index of different functional traits. Also, some functional traits, such as aboveground biomass, plant height, mean leaf length etc., were sensitive traits to grazing. However, other indicators, such as leaf numbers, stem diameter, mean leaf width etc., which were inert functional traits. Stem length, plant height and other traits were main factors which cased the decreasing of L. chinensis aboveground biomass. On the whole, phenotypic change is an important adaptive strategy of L. chinensis to long term grazing.

Leaf traits reflect the highly adaptable and self-regulatory capacity of plants to complex environmental conditions. That how they respond to climate change is one of key topics in studies of plant adaptability. This review synthesizes the current understanding on the responses of leaf size, specific leaf mass, leaf nitrogen content and carbon isotopes to climate change. The responses of leaf traits to climate change vary with different leaf structures and ecological properties. Thus, a single leaf trait cannot be used to fully reflect the responses of plants to climate change. There are still a lot of uncertainties concerning the effects of climate change on leaf traits under different scales. Studies are relatively lacking in the alpine region. This review helps us to better understand the relationships between leaf traits and climate as well as the responses and adaptation of plants to climate change. It is critical to predict the variations and evolutionary strategies of plants in response to future climate change.

Aims Leaf trait-environment relationships are critical for predicting the effects of climate change on plants. Our objective was to reveal the response of leaf traits of common broad-leaved woody plants to environmental factors on the eastern Qinghai-Xizang Plateau. Methods We measured 15 leaf traits of 332 species from 666 populations collected at 47 sites on the eastern Qinghai-Xizang Plateau. We investigated the extent of leaf trait variation in this area, and explored the response and adaptation strategies of leaf traits to environment at intra- and inter-species levels. Important findings Traits related to leaf size exhibited relatively high variation, and the leaf area was the most variant trait. Most leaf traits were significantly associated with elevation, except stomatal density. Climatic factors were important drivers of leaf trait variation because they explained 3.3%-29.5% of leaf trait variation. Meantime, temperature had the highest interpretation degree of leaf trait variation, and sunshine hours could explain the variation of most leaf traits. However, the interpretation degree of precipitation was relatively weak. In addition, the significant relationships between leaf traits and environmental (altitude and climatic) factors at intra-species level were far less than at inter-species levels. The reason for the result may be the coordinated variation and trade-off between plant traits, which make the variation of intra-species traits relatively small, and thus weaken the correlation between intra-plant leaf traits and environmental factors. Overall, leaf traits were closely related to woody plant adaptation strategies to the environment, and small, thick leaves and short petioles were selected for high-altitude plants to adapt to harsh environments such as strong winds and low temperature.

Aims In the cold life zones, snow cover is a comprehensive environmental factor that directly influences soil temperature, soil water content, light and nutrient availability. Plants in these zones develop a series of unique mechanisms involving phenological characteristics, reproductive strategies, physiology and morphology to adapt to environmental changes. This paper is focused on the responses of plant leaf traits, height and biomass partitioning to variations in snow cover thickness, in order to better understand the responses of plant functional traits and specific adaptation strategies under global climate change scenarios. Methods Three transects were established along a gradient of snow cover in an alpine meadow of Mt. Kaka, in the eastern Qinghai-Xizang Plateau. Primula purdomii, Pedicularis kansuensis and Ranunculus tanguticus, which are three widely distributed and dominant ephemerals, were sampled and studied, particularly at their blooming stages. Plant height, specific leaf area (SLA) and biomass partitioning were measured accordingly. Important findings The values of SLA in Pedicularis kansuensis and R. tanguticus were relatively greater under better soil conditions; it was smaller in Primula purdomii with thick snow cover. The relationship between aboveground biomass and belowground biomass in Primula purdomii was allometric at sites with both thick and thin snow cover. No significant relationships were found between aboveground biomass and belowground biomass in Pedicularis kansuensis and R. tanguticus at some individual sites. However, when samples of the three species were pooled, the relationships between aboveground biomass and belowground biomass were allometric at all sites, which did not support isometric scaling hypothesis. In addition, on sites with either thick or thin snow cover, aboveground biomass had greater rate of accumulation than belowground biomass; whereas on sites with medium snow cover, the rate of biomass accumulation was greater for belowground component than aboveground component. Functional traits and biomass variables were better correlated in Primula purdomii and Pedicularis kansuensis than in R. tanguticus.

Aims Altitude has prominent effects on many environmental factors, such as atmospheric pressure, temperature, precipitation, soil moisture and wind velocity. The relationship between plant functional traits and altitude are critical for predicting the effects of climate change on montane plants. Our objective is to examine the effect of altitude on community-level plant functional traits in the Qinghai Lake Basin, China.
Methods Five sites were selected with 200 m increase in altitude (3 400-4 200 m) in the Qinghai Lake Basin, China. Community structure, plant functional traits, soil property and atmospheric factors were surveyed and analyzed in this study. Community-weighted mean functional traits (CWM) was calculated according to the relative abundance of species.
Important findings The results showed that: (1) Community-weighted mean plant height (H), leaf dry matter content (LDMC), leaf C:N ratio (C:N) and leaf N:P ratio (N:P) decreased significantly along altitude, while specific root surface area (SRA) fluctuated with altitude. Specific leaf area (SLA), leaf nitrogen content (LNC) and leaf phosphorus content (LPC) increased significantly along altitude, while altitude had no significant effect on leaf carbon content (LCC), root tissue density (RTD) and specific root length (SRL). (2) The variation in CWM along altitude could be explained by species turnover more rather than intraspecific variability. N:P and LPC had a positive covariation, other CWM had a negative covariation. (3) Precipitation and 0-10 cm depth soil nutrients content explained the largest proportion change of SLA. Temperature and 10-20 cm depth soil nutrients content explained the largest proportion change of other CWM along altitude. Overall, these findings suggested that the plant communities in our study adapted to altitude through species turnover, and the non-dominant species tended to occupy opposite trait spaces to the dominant species in the Qinghai Lake Basin, China. Temperature and deeper soil nutrients content had significant effects on CWM along altitude.

Aims As vascular plants evolve from ferns to gymnosperms and angiosperms, their physiological structures and functions are assumed more adaptable to arid environment. Whether the three plant groups from early to late evolved lineages have improved their water transport and use efficiency has been studied on the basis of the morphological structure of leaf veins and stomata.Moreover, the water transportation rate was directly measured in the angiosperms. Therefore, we measured structural and functional traits related to water relations in all three plant groups simultaneously, to test the hypothesis on the evolutionary process of plant hydraulics.

Methods We selected three species in each group grown in South China Botanical Garden, Guangzhou, China, including ferns (Dicranopteris pedata, Cyclosorus parasiticus and Blechnum orientale), gymnosperms (Podocarpus macrophyllus, Podocarpus nagi and Taxodium distichum) and angiosperms (Manglietia fordiana var. hainanensis, Sindora tonkinensis and Bauhinia purpurea).

Important findings Sapwood and leaf specific hydraulic conductivities (K_S and K_L, respectively), and leaf conductance (K_leaf) significantly increased from ferns, gymnosperms to angiosperms. However, no significant trends were found in transpiration rate (E) and intrinsic water use efficiency. Meanwhile, neither the size and density of stomata nor wood density showed significant difference among three plant groups. The hydraulic functional traits (K_S, K_L and K_leaf) had significantly positive correlations with each other, but had no relationships with the two measured structural traits. Phylogenetic independent contrasts analyses showed that the coordination between K_S and K_leaf, and between K_S and E were independent of the phylogeny. Based on the nine vascular species, this study demonstrated that water transport related traits are improved as vascular plants evolved, and the co-evolution between water transport and transpiration traits were identified. For further study, it is necessary to consolidate our data with investigations of more detailed water-transport structures in more species from different evolutionary lineages.

Leaf is the most important organ for carbon-water coupling of a plant because it is the primary medium for photosynthesis. It also acts as the hydraulic bottleneck and safety valve against hydraulic catastrophic dysfunctions. The leaf economics spectrum, which reflects the balance between investments and returns of leaf economic traits, provides a useful framework for examining species strategies as shaped by their evolutionary history. Changes in leaf hydraulic traits will influence leaf economic traits as well as plant survival and growth. Exploring trade-offs between leaf hydraulic and economic traits is thus of significance for modeling carbon-water relations, understanding the mechanisms of water/carbon investments, and extending the leaf economic spectrum. In this review, we first examined the trade-offs between leaf hydraulic and economic traits. Specially, we analyzed the relationships between leaf hydraulic conductivity and hydraulic vulnerability, water potential at the turgor loss point, water capacitance, safety margin, and leaf morphological, structural and functional traits. We then discussed potential mechanisms regulating leaf hydraulic and economic traits from leaf morphology, anatomy, venation, and stomatal functions. Finally, we proposed future research to: (1) develop an integrated whole-plant economics spectrum, including carbon-nitrogen-water resources and root-stem-leaf hydraulic transport system that will help revealing ecophysiological mechanisms of plant structure-functional coupling, carbon sequestration and water use; (2) explore a generalized trade-offs among leaf hydraulic safety, hydraulic efficiency and carbon fixation efficiency to advance our understanding of the relationships between biophysical structure and physiological metabolism in plant leaf construction under drought stress; and (3) explore the carbon-water metabolic relationship and coupling of water transport and growth rate for the metabolic theory and predictions at community scale.

Aims It is very important to investigate the relationships between litter decomposition characteristics and plant functional traits in understanding the maintenance mechanism of ecosystem functions.

Methods In order to study the main driving factors that affect the leaf litters and root decomposition of different species, this study took the leaf litters and roots of six main plant species Stipa grandis, Cleistogenes squarrosa, Anemarrhena asphodeloides, Leymus chinensis, Convolvulus ammannii and Carex korshinskyi in S. grandis steppe. The litter bag method was used to study the decomposition rate constant of both leaf litters and root through 501 days of field incubation. Plant functional traits including leaf dry matter content, root specific surface area, root tissue density, contents of C, N and different cellulose components of the leaf and root litters were determined and the relationships between decomposition characteristics and functional traits of leaf litters and root across six plant species were examined.

Important findingsThe results showed that there were significant interspecific differences in leaf and root traits of six plant species. The ratios of maximum to minimum values for most traits were between 1 and 2, while the difference in some traits, such as C:N and specific surface area of roots between species was nearly 4 times. For the six plant species, the overall trend of the mass residue and decomposition rate constant of the leaf litter and root during 501 days of decomposition all showed the rapid decomposition in the early stage, relatively slow decomposition in the middle stage and the slowest decomposition in the later stage. During the decomposition process of leaf litters and roots, Cleistogenes squarrosa showed the slowest one, while the leaf litter decomposition of Anemarrhena asphodeloides was the fastest, and the root decomposition of Convolvulus ammannii was the fastest. Through the correlation analysis and stepwise regression analysis, it was found that the decomposition process of leaf litters and roots was affected by different traits in different decomposition periods. The structural carbohydrate content was the main factor affecting the early and late decomposition of litters and the early decomposition of roots, while the non-structural carbohydrate content was the main factor affecting the middle and late decomposition of roots. In addition, the decomposition rate of leaf litters in the middle stage of decomposition was mainly affected by leaf dry matter content, while the decomposition rates of roots in the middle and late stages of decomposition were also significantly affected by C:N and N content, respectively. Our results present the important guide for the prediction of carbon and nutrient cycling process in the S. grandis steppe.

Aims Global nitrogen (N) deposition not only alters soil N and phosphorus (P) availability, but also changes their ratio. The levels and ratios of N and P supply and their interaction may simultaneously influence plant seed traits. However, so far there has been no experiments to distinguish these complex impacts on plant seed traits in the field.

Methods A pot experiment with a factorial design of three levels and ratios of N and P supply was conducted in the Nei Mongol grassland to explore the effects of levels and ratios of N and P supply and their interaction on seed traits of Chenopodium glaucum.

Important findings We found that the relative contribution (15%-24%) of N and P supply levels in affecting the N concentrations, P concentrations and germination rates of seeds was larger than that (3%-7%) of N:P supply ratios, whereas seed size was only significantly influenced by N:P. Simultaneously, seed N and P concentrations were impacted by the interaction of N and P supply levels and ratios. At the same N:P, decrease in nutrient supply levels increased seed N concentrations, P concentrations and germination rates. N:P supply ratios only had a significant effect on seed size and germination rates under low nutrient levels. Overall, these results indicate that different seed traits of C. glaucum show different sensitivities to N or P limitations, leading to adaptive and passive responses under different nutrient limitations. This study presents the the first field experiment to distinguish the effects of nutrient supply levels, ratios and their interactions on plant seed traits, which provides a new case study on the influences of global N deposition on future dynamics of plant population and community.

The growth relationship between twigs and leaves is a strategy that plants enhance the ability to use space resources under environmental stresses, and elucidation of this characteristics is important for understanding the phenotypic plasticity of plants in coping with environmental heterogeneity. Our objective was to examine how Robinia pseudoacacia would vary in twig and leaf configuration in response to changes in slope aspect.

In the northern mountains of Lanzhou in Gansu Province, China, 20 transects were laid out horizontally along the contour at intervals of 50 m from an elevation of 1550 m upward in four different slope aspects, and 12 plots were set up along each transect at intervals of 5 m. A handheld GPS was used to measure latitude, longitude and altitude of each plot. Community traits were investigated and all individuals of R. pseudoacacia were used for measurements of the cross-sectional area of twigs, total leaf area, leafing intensity, and average area of a single leaf on each twig. ArcGIS was used to construct the digital elevation model (DEM). The 240 plots were categorized into groups of northern, eastern, western and southern aspects, and the standardized major axis (SMA) estimation method was then used to examine the allometric relationship between the cross-sectional area of twigs, total leaf area, leafing intensity and average area of a single leaf.

With changes in the slope aspect from north to east, south and west, the crown density, average tree height and soil moisture of the plant community displayed a pattern of decrease—increase, and the cross-sectional area of twigs, total leaf area and average area of a single leaf of R. pseudoacacia displayed a pattern of decrease—increase and the leafing intensity displayed a pattern of increase—decrease. Significant positive relationships between the cross-sectional area of twigs and total leaf area were found in R. pseudoacacia in all slope aspects (p < 0.05), and the common slope of the regressions was significantly greater than 1; significant negative relationships between leafing intensity and average area of a single leaf were found in all slope aspects (p < 0.05), and the common slope of the regressions was significantly close to -1. In addition, when the slope aspect changed from north to east, south and west, the y-intercepts in the scaling relationships of the cross-sectional area of twigs vs. total leaf area and the leafing intensity vs. individual leaf area both displayed a pattern of decrease—increase. The allometric relationship between twig and leaf with changes in slope aspect of the habitat reflected the response and adaption of plant functional traits to their biotic and abiotic environments and the investment balance mechanism of plant architecture construction.

Aims There would be a trade-off between enhancing water use efficiency and decreasing leaf construction cost in arid plants. We hypothesized that plants in lower precipitation areas could have higher water use efficiency at a given leaf construction cost compared to plants in higher precipitation areas by altering relationships between leaf functional traits (i.e. increasing area-based leaf nitrogen concentration, N_area).Methods Artemisia ordosica is a widespread species in the Mau Us sandy land. Variations of leaf construction cost of A. ordosica along a precipitation gradient and its relationships to other leaf traits such as specific leaf area (SLA), mass-based leaf nitrogen concentration (N_mass), N_area and leaf stable carbon isotopes ratio (δ ¹³C) value were analyzed.Important findings There were no significant differences in mass-based leaf construction cost (CC_m) among different precipitation areas. Although area-based leaf construction cost (CC_a) showed significant differences among different precipitation areas, they did not increase significantly with decreasing precipitation. The relationship between CC_m and SLA was not significant while CC_m positively correlated with leaf δ ¹³C value. There was a strategy shift in the positive relationship of leaf construction cost to N_area between plant-groups in the lowest precipitation (264 mm) areas and other higher precipitation (310-370 mm) areas, i.e. plants from low precipitation areas have higher N_area at a given leaf construction cost. Our results indicated that although high water use efficiency was accompanied by high leaf construction cost, the high N_area for plants from lower precipitation areas did not increase their leaf construction cost.